A simple and effective method to synthesize fluorescent nanoparticles using tryptophan and light and their lethal effect against bacteria

• Synthesis of spherical silver nanoparticles using tryptophan.
• The reduction of silver ions can be controlled through the control of the exposure time.
• Fluorescence can be observed.
• For the concentrations >25 mg/mL the growth inhibition continued to be extremely effective for the tested bacteria species.

A simple, environmentally friendly and cost-effective method was used to synthesize silver nanoparticles using tryptophan and light. To prepare the nanoparticles, the following components were used: deionized water, silver nitrate, light and tryptophan. The effects of the tryptophan concentration and light exposure time on the formation of tryptophan silver nanoparticles (Tnnps) were studied. The synthesized Tnnps were characterized using transmission electron microscopy (TEM), absorption and fluorescence spectroscopy and zeta potential measurements. The synthesized Tnnps were nearly spherical, with sizes of approximately 17 nm. In addition, the antibacterial activity of Tnnps was determined by monitoring the growth curves of strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Serratia marcescens, and Enterococcus faecalis using the microdilution test. The Minimum Inhibitory Concentration (MIC) for 4 of 5 tested bacteria was determined to be between 20.0 and 17.5 μg/mL for 48 h and between 22.5 and 20.0 μg/mL for 72 h.

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